试题与答案

某学生为测定未知浓度的硫酸溶液，实验如下：用1.00mL待测硫酸配制100mL稀

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题型：填空题

题目：

某学生为测定未知浓度的硫酸溶液，实验如下：用1.00mL待测硫酸配制100mL稀H2SO4溶液；以0.14mol·L-1的NaOH溶液滴定上述稀H2SO425.00mL(酚酞作指示剂)，滴定终止时消耗NaOH溶液15.00mL。

（1）该学生用标准0.14mol·L-1 NaOH溶液滴定硫酸的实验操作如下：

A．用酸式滴定管取稀H2SO4 25.00mL，注入锥形瓶中，滴入指示剂。

B．用待测定的溶液润洗酸式滴定管　　

C．用蒸馏水洗干净滴定管

D．取下碱式滴定管用标准的NaOH溶液润洗后，将标准液注入碱式滴定管刻度“0”以上2—3cm处，再把碱式滴定管固定好，调节液面至刻度“0”或“0”刻度以下

E、检查滴定管是否漏水　　　

F、另取锥形瓶，再重复操作一次

G、把锥形瓶放在滴定管下面，瓶下垫一张白纸，边滴边摇动锥形瓶直至滴定终点，记下滴定管液面所在刻度

①滴定操作的正确顺序是(用序号填写)；E→C→D→    →    →    →F；

②在G操作中如何确定终点？                                               。

（2）碱式滴定管用蒸馏水润洗后，未用标准液润洗导致滴定结果                   

（填“偏小”、“偏大”或“不变”）。

（3）如有1mol/L和0.1mol/L的NaOH溶液，应用0.1mol/L的NaOH溶液，原因是______________                                 _____                       ___。

（4）用标准NaOH溶液滴定时，应将标准NaOH溶液注入    __（选填“甲”或“乙”）中。

（5）观察碱式滴定管读数时，若滴定前仰视，滴定后俯视，则结果会导致测得的稀H2SO4溶液浓度           （选填“偏大”“偏小”或“无影响”）

（6）计算待测硫酸(稀释前的硫酸)的物质的量浓度(保留到小数点后二位)                   。

答案：

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参考答案：对

考点：化学实验的基本操作化学实验安全危险化学品的标志化学药品的变质
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